Mixed CRC Screening Messaging. Confusing? Some Docs Think So

Alicia Gallegos

October 12, 2023

Recently updated colorectal cancer (CRC) screening guidance from the American College of Physicians (ACP) is raising concerns among some specialists.    

The ACP's clinical guidance, published in Annals of Internal Medicine in late July, called for CRC screenings to start at age 50 in average-risk individuals who are asymptomatic. This recommendation, however, conflicts with guidelines from the American Cancer Society (ACS) and the US Preventive Services Task Force (USPSTF), which, in 2021, officially lowered the recommended initial age of screening to 45.

Following the ACP's announcement, several professional organizations, such as the American College of Radiology, criticized the new guidelines, calling them "a step backward" and warning they may hinder recent gains against CRC. 

Some physicians believe the discordance will confuse patients and lead to varying referral practices among primary care physicians. And while insurers will likely continue to pay for screening procedures based on the USPSTF guidelines, which dictate insurance coverage, some physicians worry that insurers could create additional roadblocks for CRC screening coverage, such as requiring prior authorization.

"We're in a conflicted space on this issue as a country," said John L. Marshall, MD, a GI oncologist and director of The Ruesch Center for the Cure of GI Cancers at Georgetown University, Washington, DC.

Ultimately, the physician community wants an inexpensive screening test that's effective at preventing cancer and deaths, but the evidence thus far doesn't necessarily support colonoscopy as that test, said Marshall, also chief medical officer for Lombardi Comprehensive Cancer Center.

Although colonoscopy can prevent CRC by removing precancerous polyps and can reduce deaths from cancer, it has not been shown to lower all-cause mortality, Marshall explained. A recent meta-analysis, for example, found that, aside from sigmoidoscopy for colon cancer screening, no other cancer screening modalities meaningfully changed life expectancy.

"That's why we're struggling," Marshall said. "We're emotionally invested in having screening available to younger people because we're seeing colon cancer in younger people. So, we want it to move earlier, but it's expensive and it's invasive."

Docs Debate Differing Guidance

The new ACP guidance, based on a critical review of existing guidelines, evidence, and modeling studies, argues that the potential harms of screening average-risk individuals under age 50 may outweigh the potential benefits.

The benefits of screening, of course, include identifying and removing precancerous lesions or localized cancer, while the potential harms include false-positives that may lead to unnecessary additional tests, treatments, and costs. More invasive screening procedures, such as colonoscopy, can also come with their own risks, including serious bleeding and perforation.

For colonoscopy, for instance, the ACP team determined that starting screening at age 45 vs 50 could prevent 3 additional CRC cases per 1000 individuals screened (58 vs 61) and 1 CRC death (27 vs 28) over the recommended screening timeframe. On the flipside, screening starting at age 45 could increase the incidence of gastrointestinal or cardiovascular events (14 vs 16).

"Even if we assumed the modeling study had no limitations and accepted the results at face value, we would conclude that the small estimated benefits and harms roughly balance each other out, resulting in an inadequate net benefit to warrant CRC screening in average-risk adults aged 45 to 49 years," Amir Qaseem, MD, PhD, and ACP co-authors write.

Family physician Kenny Lin, MD, MPH, believes the updated ACP guidelines are reasonable, and points out the ACP is not the first group to disagree with the USPSTF's recommendations. 

"I think the [ACP] guidelines make a lot of sense," said Lin, who practices in Lancaster, Pennsylvania. The American Academy of Family Physicians "also did not endorse the recommendations to start screenings at 45." In its 2021 updated guidance, the AAFP recommended screening for CRC starting at age 50, concluding there was "insufficient evidence to assess the benefits and harms of screening" in the 45 to 49 population.

However, Jason R. Woloski, MD, a family physician based in Wilkes-Barre, Pennsylvania, expressed concern that the differing guidelines will confuse patients as well as present challenges for primary care physicians.

"I feel like we took the last couple of years convincing people that earlier is better," said Woloski, an associate professor of family medicine at Geisinger Commonwealth School of Medicine. "It can send a mixed message to a patient after we've been stressing the importance of earlier [screening], and then saying, 'Maybe we got it wrong; maybe we were okay the first time.'"

Mark A. Lewis, MD, a GI oncologist, had a similar initial reaction upon hearing about the updated guidelines: "The lack of synchronization across groups is going to create confusion among patients."

Although he could not say definitively whether the recommendations will impact GI oncologists, because he only sees patients with advanced CRC, he does see the demands in primary care and gastroenterology shifting.

"I think the much bigger impact will be on primary care physicians and gastroenterologists," said Lewis, director of gastrointestinal oncology at Intermountain Healthcare in Murray, Utah. "My best guess is that the procedural burden on the latter will be mitigated by more stool testing ordered by primary care physicians. Patients may understandably prefer the convenience and lack of invasiveness of home-based fecal testing, but a positive FIT [fecal immunochemical test] without a follow-up scope is an incomplete screening."

Marshall, however, had a different take. He does not envision the updated guidelines having much of a practical impact on physician practice. Most of the country is already not receiving proper colon cancer screenings, he said. Research shows more than 40% of Americans skip standard CRC screenings. Even anecdotally, he noted, friends in their 60s come to him and admit they haven't had a colonoscopy yet. 

Potential Impact on Patient Outcomes, Costs

Beyond mixed messaging, some experts worry that pushing CRC screening later could mean cancers are caught later, when they're more advanced.

Finding cancers earlier, when they are easier and less expensive to treat, make earlier CRC screenings worthwhile, Woloski explained.

Lewis sees earlier screening as a way to stop a tumor from progressing before it can really pick up steam.

"To me the biggest advantage of colonoscopy is the interruption of the adenoma-to-carcinoma sequence, whereby a polyp that is completely removed cannot become an invasive adenocarcinoma," Lewis said. "We've also had evidence for well over a decade that flexible sigmoidoscopy, which doesn't come close to visualizing the entire colon, can confer a survival benefit." 

Another concern is the potential effect on insurance coverage.

Medicare and other insurers use USPSTF guidelines to make coverage decisions. However, because of this mixed message, Woloski questioned whether there would be more challenges regarding insurance coverage. "Does it mean primary care doctors are going to have to preauthorize a lot of these screenings even if you have shared decision-making with the patient?" he asked.

When it comes to screening referrals, Douglas A. Corley, MD, PhD, a gastroenterologist at Kaiser Permanente in Northern California, said it's critical for primary care physicians to educate patients about the differing views on screening benefits and harms as well as the different screening options.

"Given the different opinions, it is important to let people in this age group know that screening is an option recommended by some groups," Corley said. "Colorectal cancer screening is very effective for decreasing the risk for death from colorectal cancer, which is the second leading cause of cancer death in the United States. Making sure all eligible people know this is an option provides the best way for patients to have an informed choice."

Lin has already begun talking with patients about the differing recommendations. He said it's helpful to simplify the issue and focus the conversation on what patients value most. For more assertive patients whose priority is finding every possible cancer early, starting screenings at age 45 may be reasonable, he said, whereas other patients may not find the process or possible side effects worth it.

"And then you have the middle group that decides, 'Yes, I want to start at 45, but I want the fecal test. I don't want to just jump into colonoscopy.' " Lin said. "That would be kind of a compromise where you'd be starting screening earlier, but not subjecting yourself to something that has more potential for harms."

Woloski said he plans to continue making referrals based on the USPSTF recommendations. 

"With every screening, it is about informed decision-making with the patient, but I think for now, since USPSTF still supports the earlier screening, I will probably stick with offering it earlier," he said.

But when deciding on the appropriate timing for evaluating CRC, the most important distinction is between screening and diagnosis, Lewis added. 

"The former is only appropriate in patients who are truly asymptomatic and who are truly average-risk," he said. "The latter is critical in any patient with symptoms. I cannot count the number of times I have seen blood in the stool discounted as hemorrhoids without even an exam, digital rectal, or scope, to demonstrate that hemorrhoids are present and the culprit for blood loss."


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